What value of n makes the equation true?

Answers; a) 135 degree’s b) 30 degree’s c) 180 or 0 degree’s d) 90 degree’s

Is it true or false i’m trying to pass this test so i can leave school

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%